Apparatus for reducing unwanted asymmetric forces on a driver head during a golf swing

ABSTRACT

An aerodynamic apparatus that is built into or attached to a body of a golf club head to cause the airflow over the body to transition from smooth to turbulent at a defined length from the striking face of a club. The device reduces asymmetric variations in the boundary layer separation point that cause unsteady forces on the club head and create excess unpredictable cavitation behind the club head. The device is aligned essentially parallel to the intersection of the striking face and the body and is situated near the maximum thickness of the body cross-section. The device is comprised or a small strip of material, a string, a gap, a ridge, a groove, a step up, a step down, a surface curvature breakpoint, or a series of geometric patterns that traverses around the entire perimeter of the body surface either continuously or in broken segments.

BACKGROUND OF INVENTION

[0001] The invention relates to the aerodynamic design of a golf club head and specifically to the reduction of unwanted asymmetric aerodynamic forces on the driver or fairway-wood head just prior to the moment of impact. The reduction of these forces allows the player to hit the ball on the center of percussion, or sweet spot, more easily, which creates longer, more accurate drives off the tee and from the fairway. This invention assists all levels of golfers to improve their performance. The invention does not apply to irons or putters.

[0002] Many advances have been made in the field of driver or fairway golf club head design including material advances, trampoline effects, and drag reduction, but nothing has been invented to reduce the forward, lateral, asymmetric forces that introduce error at the moment of impact.

[0003] At the moment of impact a driver club head travels as high as one hundred and forty miles per hour. The average player creates head speeds of approximately eighty to one hundred miles per hour. Because the distance from the driver head to the club grip creates a long lever, very small forces on the local head translate into much larger moment forces at the players hands. These forces must be continually counteracted to guide the sweet spot of the club head to strike the ball.

[0004] In a normal swing the club head twists as it rotates toward the impact area and the club head traverses through a non-uniform wind velocity profile. The twisting creates a changing angle-of-attack between the golf club head and the golf club path. The non-uniform wind velocity is the result of the players' bodies, trees, buildings, spectators, tee boxes, or tee mounds, interfering with the otherwise smooth wind profile. These phenomenon cause the airflow around the face of the club head to transition from a laminar, or attached, condition, to a turbulent, or separated, condition at different lengths from the club head face around the club head. It is this aerodynamic variation that causes excess unwanted lateral forces the club head and excess non-uniform cavitation in the airflow behind the club head.

[0005] The prior art contains numerous attempts at reducing drag and turbulent regions behind the club head. U.S. Pat. No. 5,435,558, entitled GOLF CLUB HEAD WITH AERODYNAMIC DESIGN, tries to control the vortices behind the club but does nothing to control the separation distance from the club head face. U.S. Pat. No. 5,529,303, entitled GOLF CLUB HEAD, tries to control the airflow by channeling it through the club head, but does nothing to control the flow on the top, bottom, and side surfaces. U.S. Pat. No. 6,027,414, entitled GOLF CLUB WITH AERODYNAMIC SHAFT AND HEAD, does not address the separation distance from the club head face. These patents, others like them, and the patents cited during the prosecution thereof, do not affect the variation in boundary-layer separation distance around the club head perimeter. Further, technology from the prior art can not be retrofitted on all existing clubs like the present invention.

SUMMARY OF INVENTION

[0006] The present invention is an improvement on prior art golf club heads, and overcomes the problems noted above by providing, at a point sufficiently far forward to cause an abrupt transition of the boundary layer and sufficiently far aft to prevent reattachment, a discontinuity in the surface to cause an aerodynamic disturbance. The discontinuity, or trip strip, is approximately equidistant from the club head face and is situated near the maximum thickness point. The trip strip is of sufficient thickness to effect transition without a noticeable rise in drag force.

[0007] The invention also pertains to the retrofit of trip strip technology on existing golf club heads to bring equivalent benefits to players that do not wish to replace their existing clubs to take advantage of the performance improvement.

[0008] Other features and benefits of the present invention, like the satisfaction of golf equipment requirements of regulating bodies, will become apparent from the following description of the invention which refers to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0009] The invention will be better understood by reference to the accompanying drawings, wherein:

[0010]FIG. 1 is a representation of a golf driver or fairway club head with trip strip technology either built into the club head or attached to an existing club head.

[0011]FIG. 2 is a side view of a club head with trip strip technology.

[0012]FIG. 3 is a top view of a club head with trip strip technology.

[0013]FIG. 4 is a representation of a second embodiment of a golf club head with trip strip technology that is attached to an existing club and twisted around the hosel.

[0014]FIG. 5 shows a magnified representation of alternate cross-sectional shapes for trip strips.

[0015]FIG. 6 shows a magnified representation of alternate patterns for trip strips.

[0016] These figures are provided to complete the description given here as an illustration but do not impose any limitation.

DETAILED DESCRIPTION

[0017] The golf club head 1 of the present invention is shown as the preferred embodiment in FIGS. 1 through 3. A discontinuity, or trip strip 2 in the surface acts to disrupt the laminar flow over the forward part of the club head 3. The trip strip lies essentially parallel to the club face 4 near the maximum thickness of the club head cross-section 5. The airflow is uniformally disturbed around the majority of the surface perimeter and is forced to transition to a turbulent flow which does not reattach to the aft end of the club head 6. The trip strip 2 can be built into the club as a technical feature or added to existing clubs as a retrofit.

[0018] A second embodiment of the golf club head with trip strip technology is shown in FIG. 4, where the trip strip 2 is wrapped around or attached to the hosel 7 to prevent slippage and loss.

[0019]FIG. 5 shows a magnification of a representation of several variations of other styles of trip strips that could produce an equivalent aerodynamic effect. Cylindrical shapes 12, gaps 13, grooves 14, a step down 15, surface curvature breaks 16, or merely higher surface roughness like sandpaper 17 could also create the desired aerodynamic disturbance.

[0020] Further, the trip strip need not be continuous lines. See FIG. 6. Dashes 8, circles 9, triangles 10, or dotted line trip strips 11 would serve the same purpose.

[0021] It should also be evident that the thickness and width of the trip strip cross-section could vary in size and still fall within the scope of this patent.

[0022] So it is evident that the golf club head with trip strip technology in the present invention has advantages as follows:

[0023] 1. Control of the transition point of the airflow around the club perimeter from laminar to turbulent flow.

[0024] 2. Reduction in lateral side forces caused by varying airflow transitions while club is undergoing changes in angle-of-attack and being subjected to non-uniform wind velocity profiles.

[0025] 3. Reduction in asymmetrical cavitation behind the club head during a swing due to more uniform transition to turbulent flow around club head.

[0026] 4. Increased ability of golfers to maintain their intended swing path and club head rotation through reduction of uncontrollable and unpredictable lateral forces.

[0027] 5. Increased likelihood of golfer to hit center of percussion, the sweet spot, on club head face with desired club head incidence.

[0028] 6. Improved golf driver accuracy and distance off the tee and off the fairway due to golfer hitting sweet spot more often with intended club head alignment.

[0029] 7. Applicability of trip strip technology to existing golf clubs through retrofitting clubs with an adhesive, elastic, or other disturbance.

[0030] While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications may be made therein and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention. 

1. A golf club head comprising a striking face for striking a golf ball, a body attaching to the striking face and extending around the perimeter of the striking face, a discontinuity in the body for controlling a boundary layer transition point on the body, and an aft surface opposite to the striking face and closing the body.
 2. The golf club head of claim 1, wherein the discontinuity is essentially parallel to the intersecting edge of the striking face and the body.
 3. The golf club head of claim 1, wherein the discontinuity is situated near the maximum thickness point of the cross-section of the body.
 4. The golf club head of claim 1, wherein the discontinuity is located one half inch to two inches from the intersecting edge of the striking face and the body.
 5. The golf club head of claim 1, wherein the discontinuity is large enough to disrupt the boundary layer but small enough not to contribute a substantial amount of drag force.
 6. The golf club head of claim 1, wherein the discontinuity is comprised of an abrupt change in surface curvature, a gap, a step, a grove, or surface roughness.
 7. The golf club head of claim 1, wherein the discontinuity is comprised of segments of geometric shapes, circles, triangles, dashes, or dots.
 8. A golf club head comprising a striking face for striking a golf ball, a body attaching to the striking face and extending around the perimeter of the striking face, a removable discontinuity on the body for controlling a boundary layer transition point on the body, and an aft surface opposite to the striking face and closing the body.
 9. The golf club head of claim 8, wherein the removable discontinuity is essentially parallel to the intersecting edge of the striking face and the body.
 10. The golf club head of claim 8, wherein the removable discontinuity is situated near the maximum thickness point of the cross-section of the body.
 11. The golf club head of claim 8, wherein the removable discontinuity is located one half inch to two inches from the intersecting edge of the striking face and the body.
 12. The golf club head of claim 8, wherein the removable discontinuity is large enough to disrupt the boundary layer but small enough not to contribute a substantial amount of drag force.
 13. A trip strip to attach to a body of a golf club head to control a boundary layer transition point on the body.
 14. The trip strip of claim 13, wherein the attachment is made by adhesive, adhesive-backing, or elastic tension.
 15. The trip strip of claim 13, wherein the trip strip is designed to be applied essentially parallel to a striking face of the golf club at approximately the maximum cross-section thickness of the body.
 16. The trip strip of claim 13, being comprised of any number of various cross-sections designed to disrupt the boundary layer on the body.
 17. The trip strip of claim 13 wherein the trip strip is large enough to disrupt the boundary layer but small enough to avoid a substantial increase of drag force.
 18. The trip strip of claim 13, wherein the trip strip is formed of segments of lines, geometric shapes, circles, triangles, or dashes.
 19. The trip strip of claim 13, wherein the trip strip is wrapped around a hosel of the golf club head to reduce slippage and loss. 